1. Field of the Invention
The present invention relates to a magnetic material using no heavy rare earth elements, and a motor using the magnetic material.
2. Background Art
Patent Documents 1 to 5 disclose conventional rare earth-sintered magnets containing a fluoride or an oxy-fluoride. Patent Document 6 discloses mixing a rare earth fluoride fine powder (1 to 20 μm) and a NdFeB powder. A Brazilian Patent of Patent Document 7 describes an example of Sm2Fe17 being fluorinated.    Patent Document 1: JP Patent Publication (Kokai) No. 2003-282312A    Patent Document 2: JP Patent Publication (Kokai) No. 2006-303436A    Patent Document 3: JP Patent Publication (Kokai) No. 2006-303435A    Patent Document 4: JP Patent Publication (Kokai) No. 2006-303434A    Patent Document 5: JP Patent Publication (Kokai) No. 2006-303433A    Patent Document 6: U.S. Patent No. 2005/0081959    Patent Document 7: Brazilian Patent No. 9701631-4A
Conventional inventions described above are substances obtained by reacting a Nd—Fe—B based magnetic material or a Sm—Fe based material with a compound containing fluorine, and particularly disclose a lattice dilation and an effect on raising the curie point presumed to be due to the incorporation of fluorine atoms by the reaction of Sm2Fe17 with fluorine.
However, the disclosed SmFeF-based material has a low curie point of 155° C. and an unknown magnetization value, and no analysis revealing that fluorine is present in its main phase is disclosed. Even if fluorine is detected by an analysis of a whole sample having been subjected to a fluorination treatment in the analysis of fluorine after the fluorination treatment, the presence of fluorine in the main phase has not been verified. This is because various types of fluorides are formed on the surface of the treated material after the fluorination treatment, and the fluorine concentration detected by means that detects fluorine together with fluorine in the fluorides on the surface does not indicate that the main phase (a ferromagnetic having a main structure constituting crystal grains and powder) contains fluorine. Even if a main phase contains fluorine, since the fluorination treatment progresses from the surface of the main phase, a phase having a high fluorine concentration in the vicinity of the surface and a phase having a low fluorine concentration in the vicinity of the center are formed, and the difference in the crystal orientation between these phases different in the fluorine concentration causes various types of defects and a decrease in the coercive force. Therefore, no practical permanent magnetic material cannot be provided unless the crystal orientation difference is controlled.
On the other hand, in the Nd—Fe—B based magnet, the coercive force is increased by use of a fluoride containing a heavy rare earth element. The fluoride is not produced by the reaction of fluorinating the main phase, but the heavy rare earth element reacts with or diffuses into the main phase. Since such a heavy rare earth element is expensive and rare, the decrease in heavy rare earth elements poses a problem from the viewpoint of the environmental protection. Light rare earth elements, which are less expensive than heavy rare earth elements, are Sc, Y and elements of atomic number 57 to 62, and some of the elements is used for magnetic materials. A material most mass-produced among iron-based magnets other than oxides is a Nd2Fe14B-based magnet, but in order to secure the heat resistance, the addition of a heavy rare earth element such as Tb or Dy is essential. Since a Sm2Fe17N-based magnet cannot be sintered and generally used as bond magnets, it has a drawback in the performance. An R2Fe17 (R is a rare earth element) based alloy has a low curie point (Tc), but since a compound into which carbon or nitrogen has intruded has a high curie point and high magnetization, the alloy is applied to various types of magnetic circuits.
In order to mass-produce materials into which fluorine atoms have intruded as magnets of such interstitial compounds, magnetic characteristics such as the coercive force and the residual flux density need to be secured by controlling the crystal orientation in magnetic powders or crystal grains of fluorides having the rhombohedral, tetragonal or monoclinic crystal structure in their parent phase, for example, fluorides of a Th2Zn17-type Sm2Fe17F3 alloy, a ThMn12-type NdFe11TiFx alloy, an R3(Fe, Ti)29-type Sm3(Fe, Ti)29F5 alloy, and a Sm3(Fe, Cr)29Fx alloy.
The present invention has been achieved in consideration of the above-mentioned viewpoints, and has an object to provide a magnetic material improved in characteristics in the magnetic material using no heavy rare earth element as a scarce resource, and a motor using the magnetic material.